The Effect of Surface Energy of Woven Drainage Channels in Coalescing Filters

The surface energy, or wettability, of the fibers in coalescence filter media controls the performance of coalescing filters. High surface energy fibers capture and hold onto droplets, slowing their movement through the filter and hence increase coalescence between drops. Low surface energy fibers allow drops to slip through the filter with little or no hindrance but do not contribute significantly to the coalescence. In this work we present experimental data on the performance of composite filters made of high surface energy fibers with layers of low surface energy woven mats of fibers as drainage channels. Drainage channels provide pathways for coalesced liquid to rapidly flow out of the filter without compromising with the capture efficiency. Hence the saturation or hold-up of liquid, in the filter decreases. This reduces the pressure drop, and increases the filtration index and filter life. In this paper, filters were fabricated by layering woven and nonwoven polymer fiber drainage channels into non-woven glass fiber filter media. The effect of the presence and geometry of the drainage channels on the filter performance was evaluated. The high surface energy glass fibers provide the desired coalescence while the low surface energy polymer fibers of the drainage channels reduced the filter saturation. The experimental results show that filter media embedded with Teflon® fiber drainage channels at 45° downward angles had the overall best performance